Control torque and motion device through a wall



-MQY 18, 1965 e. R. BROWN ETAL 3,183,727 CONTROL TORQUE MOTION DEVICE THROUGH A WALL Filed June 18.- 1962 a Sheets-Sheet 1 IN EN gzz uziz ATTORN EYS y 1955 e. R. BROWN ETAL 3,183,727

CONTROL TORQUE AND MOTION DEVICE THROUGH A WALL Filed June 18, 1962 s Sheets-Sheet 2 LOW TORQUE HIGH ['4 LIQUID LEVELS O Ow O 2; m 5 '2 G J g E S l 0.. Q 0

HIGH TORQUE LOW ANGULAR MOTION OF MOVEMEN:

LIQUID LEVELS MOMENT ARM i v I v n v 4 v I I I v a a 5 e y 1965 a. R. BROWN ETAL 3,183,727

CONTROL TORQUE AND MOTION DEVICE THROUGH A WALL Filed June 18, 1962 3 Sheets-Sheet 3 74;? 2 PRIOR ART PRIOR ART TORQUE TORQUE ANGULAR MOTION ANGULAR MOTION DEFLECTION DEFLECTION CURVE Z UDJ CURVE 2 o a MOVING 2 g WIRE g -STATIONARY WIRE E DEFLECTION DEFLECTION ATTORNEYS United States Patent 3,183,727 CONTROL TORQUE AND MGTION DEVICE THROUGH A WALL George Rehert Brown, Lansdaie, and Emile James Fry,

Ardsley, Pa., assignors to Yarnall-Waring Company,

Philadelphia, Pa, a corporation of Pennsylvania Filed June 18, 1962, Ser. No. 203,352 11 Claims. (Cl. 7417 .8)

The present invention relates to mechanism which may be utilized to transmit torque and motion through a wall from or to a closed space.

A purpose of the invention is to introduce an initially curved wire into laterally supporting relation in an initially straight tube extending through and sealed to a pressure wall around the outer periphery of the tube, so that the tube and wire achieve a curvature in a beam section, preferably a cantilever beam section, there being clearance between the wire and the tube, to elastically deflect the wire and tube combination at a free point on the beam in a direction transverse to the plane of the curvature of the tube while leaving the beam laterally free from restraint at the point where it is deflected, and to maintain by the lever arm on the wire outside the tube a torque level determined by the elastic residual stress of the wire against a biasing or actuating element responding to the torque so that the torque will build up steeply with deflection both when the lever arm is clamped and when it moves through a limited range of travel. The tube will preferably be closed at the free end and will always be closed at the free end where there is a difference in pressure.

A further purpose is to obtain a greater range of output for a smaller range of actuating motion in a wire and tube device.

A further purpose is to maintain the wire free from rigid fastening through the length within the tube.

A further purpose is to anchor the wire to the tube adjacent the end of a cantilever beam in one optional embodiment of the invention, or to leave the wire free at the end in another form.

A further purpose is to simplify the calibration of a wire-in-tube motion transferring device by utilizing a tube which is straight when free from elastic deflection, which is elastically deflected by a wire of predetermined'curvature, and which deflects the wire and tube combination into a curve within the elastic limit of both.

A further purpose is to utilize a moment of inertia of the tube which is one to twenty times the moment of the inertia of the wire and preferably between four times and eight the moment of inertia of the wire.

A further purpose is to increase the economy of manufacture and of calibration of the wire and tube units.

A further purpose is to obtain closer control of the operative characteristics of the wire-in-tube units.

A further purpose is to obtain closer control on multiple resistance levels of actuating devices connected with wire and tube units.

A further purpose is to develop a resistance range which is confined to a smaller range of actuator motion than with other wire and tube devices.

A further purpose is to utilize the suitably selectively variant prestress of the wire to adapt a wire and tube system to various actuating requirements and particularly to various initial loads by using different wires of different initial curvatures to establish the desired level.

A further purpose is to utilize the relatively shallow curve of a prestressed wire of small section consistent with the initial load applications rather than using a heavier wire without prestress. The prest-ress in effect can substitute for the initial load which would otherwise require a heavier wire.

3,183,727,: Ce Patented May 18, 1965 further purpose is to combine straight tubes and initially curved Wires of different modulus of elasticity so as to obtain moment of inertia values desired consistent with variable commercial structural sizes, utilizing for example non-ferrous metals of lower modulus for either the wire or the tube as desired, in combination with metals of higher modulus for the other cooperating element, either the tube or the wire.

A further purpose is to permit the tube to be made of metals of different modulus of elasticity or of difiereut coefficients of expansion or both so as to respond to temperature in a temperature sensing device.

A further purpose is to obtain a predetermined torque slope without being dependent upon the curvature of the tube.

A further purpose is to obtain a steep curve of torque output plotted against deflection of the free end of the wire-in-tube device of the character which is not possible in the prior art with the same wire and the same tube physical properties and geometry where the wire and tube have matching curvature before assembly.

A further purpose is to combine the relatively large motion obtained with shallow curved wires and tubes with a high torque level that is obtained with sharply curved wires and tubes by using a sharply curved wire with an initially straight tube.

A further purpose is to use a wire which will be urged to follow the tube motion or curvature of the tube by bending the tube by the residual stress from the wire, the positive action of the wire being caused by the inherently locked-in prestress and the fact that the wire attempts to seek its lowest energy level.

In the drawings I have chosen to illustrate a few of the numerous embodiments in which the invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

FIGURE 1 is a plan view of a suitable wire for use in a wire and tube device of the invention.

FIGURE 1a is a view similar to FIGURE 1, using a wire of different curvature in the beam section.

FIGURE 2 is a plan section of a tube which will be used in the wire-in-tube combination of the invention extending through a pressure wall and straight in all directions prior to insertion of the wire.

FIGURE 3 is a plan section of the wire and tube combination of the invention extending through a pressure wall, the beam section having taken on a curvature due to the curvature of the Wire.

FIGURE 4 is an enlarged section of the wire-in-tube combination of the invention on the line 44 of FIG- URE 3.

FIGURE 5 is a front elevation of the wire-in-tube combination of the invention omitting the pressure wall.

FIGURE 6 is an enlarged front elevation corresponding to FIGURE 5 but including the switches which have been omitted in FIGURE 5 for clarity in illustration.

FIGURE 7 is a fragmentary sectional perspective of the end of the wire-in-tube combination, showing the wire physically attached to the tube in this form whereas it is not physically attached in the form of FIGURES 1 to 6 inclusive.

FIGURE 8 is a transverse section similar to FIGURE 4 but showing a modification.

FIGURES '9 to 14 are curves useful in explaining the invention.

FIGURE 9 illustrates the relation of torque as ordinate against deflection as abscissa for a prior art wire-in-tube device in which both the wire and the tube are initially bent with a gradual curvature.

FIGURE 10 plots for the prior art device of FIGURE 9 a relation of angular motion as ordinate to deflection as abscissa.

FIGURE 11 plots torque as ordinate against. deflection as abscissa for a prior art device in which the wire and the tube are initially bent more sharply than in the 7 case of FIGURES 9 and 10.

FIGURE 12 plots angular motion as ordinate against deflection as abscissa for the prior art wire and tube com bination of FIGURE 11.

FIGURE 13 plots torque as ordinate against deflection as abscissa for the device of FIGURES 1 to 6 of the present application.

FIGURE 14 plots angular motion as ordinate against deflection as abscissa for the device of FIGURES 1 to 6.

In all of FIGURES 9 to 14 the scales of deflection, torque and angular motion are the same.

FIGURE 15 plots torque as ordinate against angular motion as abscissa for the device of the present invention.

FIGURE 16 is a diagram showing the vertical positioning of the points of wire-in-tube deflection at which actuation of various switches takes place.

FIGURE 17 shows a diagrammatic vertical section of a wire and tube device of the invention, altering changes in the point of loading of the cantilever beam.

In the prior art, as illustrated by Walter J. Kinderrnan US. Patent 3,067,623, issued December 11, 1962, for Transmission of Motion From Closed Space, wire and tube devices are illustrated which mainly employ an initially curved tube and an initially curved wire, the wire being inserted within the tube, and having a curvature which may be the same as, or different from the direction of curvature of the tube. In some forms the wire may be free from anchorage with the tube and in some forms the wire may be anchored to the tube. These devices have been used commercially to transmit motion from a closed space such as liquid level alarm column (boiler water level alarm column) and they provide snap actuation.

This previous wire and tube device has'presented certain problems from the standpoints of convenience in manufacture and ease of calibration.

The device of the invention, unlike the commercial form of the Kinderman device, obtains a wider range of output movement for a given motion at the input end, and a wider range of torque for a given range of input motion.

The device of the present invention utilizes an initially inherently straight tube, and an initially inherently curved wire, the wire and tube being combined to give a curved wire and tube device having a greater radius of curvature than the initial radius of curvature of the wire. This greatly simplifies manufacture since it is no longer necessary to employ a predetermined curvature of the tube or to calibrate or standardize the tube curvature. By substituting different curvature of wire in the predetermined straight tube various curvatures of the wire and tube device can be obtained within the elastic limit of both the wire and the tube. Furthermore, by varying modulus of elasticity of the tube and wire combination, and adjusting geometry of the tube and wire, various moments of inertia of the tube and wire respectively can be employed, desirably within the range in which the moment of inertia of the tube is between one and twenty times the mit linear motion transverse to the plane of curvature of the tube. It had one torque level at all times and did not indicate variation of torque. In the transmission of rotary motion no utilization was made of the variable control characteristics which result from a variable actuator. The actuator in rotary motion is consistent in its tube to wire relation, whereas in present device functions through the variations in the torque relations of a beam.

Thus, by the present invention a very inexpensive and simple mechanism is provided from the standpoint of both manufacture, inspection and calibration, which transmits a large range of torque or causes a large range of motion on the wire lever arm for a small range of beam movement.

While the device of the invention in its best application may be employed in electric switching, it can operate other types of indicating, recording, and control mechanism including pneumatic controls as desired.

Considering first the form of the invention shown in FIGURES 1 to 6, we there illustrate a wire 26 having a curved portion 21 through the length which is to be placed in the tube and having a suitably transversely bent lever arm portion 22 which is to be outside the tube.

The wire in the preferred embodiment will generally be of metal and in most cases will be of a metal of a high modulus of elasticity in tension or Youngs modulus such as steel, stainless steel and other alloys of high corrosion resistance and heat resistance. Metals of higher modulus of elasticity may be used such as tungsten in special cases.

The cross section of the wire in the preferred embodiment will be circular although other cross sections of wire such as oval, rectangular, polygonal, and the like may be used if desired.

The wire is used in cooperation with a tube 23, which has a straight shape in the beam portion when free from the wire indicating either initial absence of residual stress or balanced stress as desired. The tube extends through an opening 24 in a wall 25 of a closed space, so that the bulk of the extent of the tube will preferably be inside (though it could conceivably be outside the closed space) and motion is transmitted through the wall.

One of the great advantages of the device of the in- ,vention is that it can operate notwithstanding a substantial pressure differential between the inside and the outside order of hundreds or even thousands of p.s.i.

The tube where it and the pressure wall are of metal will be united to' the pressure wall as at 26 by brazing, welding orother suitable means.

The tube may be of any suitable material, preferably a metal. It will be of course understood that a glass tube could be used. In the case of metal, the tube may be of ferrous or nonferrous metal, depending upon the desired modulus of elasticity relationship with the wire, although the tube in many cases will preferably be of a corrosion resisting material such as stainless or heat-resisting steel. In some cases the tube will be of beryllium, copper, bronze, brassQphosphor, or Inconel.

The cross section of the tube inside and outside will preferably in many cases be circular as shown, although a various desirable cross sections may be employed, such as oval, square, or polygonal. The tube where it ends in the pressure space has a free end 27 which is closed against pressure transmission, for example, by brazing or welding, a convenient form as shown having a hook or eye 27 inserted asby brazing or welding at 28 so as to close the outer end.

The tube has an open end which in the preferred em- V bodimentshown will be on the opposite side of the presthe present invention offers several advantages which were 7 not present in the predetermined arcuate device for controlling the travel of the outer end of the cantilever beam. This was employed as a followup device. It did not transsure wall 25. The curved portion 21 of the wire 20 is inserted in the tube, bending the tube into a curved beam 30 having a radius of curvature R which is larger than the radius of curvature R of the wire before it is inserted 'in the tube.

achieved by the initial curvature of the wire, so that the wire and tube combination at the deflected end are laterally free in the plane of the curve which corresponds to the plane of the paper in FIGURE 3. The beam will be loaded or deflected as later explained transverse to the plane of the curvature or transverse to the plane of the paper in FIGURE 3.

As shown in FIGURE 4 the wire in the wire-in-tube combination at the cantilever beam portion tends to rest at 31 against one side of the bore 32 of the tube, and in the form shown tends to engage the tube at frequent intervals along the length of the tube or in fact in the preferred embodiment rather continuously along the length of the tube.

One of the purposes performed by the tube is to act as a counter-balancing or restraining force against the tendency of the wire to bend the tube so that an equilibrium relationship is achieved in the plane of curvature between the tendency of the wire to bend the tube and the tendency of the tube to resist bending by the wire.

At the same time, the tube and wire perform a mutual bearing function more or less continuously along their length and each tends to deform the other to an equilibrium curvature. The tube also acts as a pressure wall, and since it is very small in sectional cross section and efiicient in configuration to resist pressure, it is very effective to withstand higher pressures without crushing.

It will be evident that it is important in the device of the invention that both the tube and the wire, when the wire is inserted in the tube, be not plastically deflected but that both be within their elastic limit so that they will respond elastically.

Considering now the form of FIGURE 6, a suitable point along the beam section of the curved wire-in-tube combination is deflected transverse to the plane of curvature, as for example by a displacer 33, which for example can be applied to the eye 27 as by a suitable cable. Without intending to limit to a particular application of the device or to a particular manner of applying the load it will be evident that in one form of the device the load may be a displacer 33 submerged in a liquid such as water in a boiler, and therefore having a variant downward pull on the point of load application to the beam depending upon the depth of the water in accordance with Archimedes principle.

In the preferred embodiment of the device as shown in FIGURE 6 the lever arm 22 of the wire is interposed between and engages the actuating lever 34 of a suitable sensitive switch 35, the actuating lever 34 being pivoted at 36, and the actuating lever 37 of a suitable sensitive switch 38, the actuating lever being pivoted at 40. It will be understood that switch 35 has an operating plunger 41 engaging the lever 34 and continuously internally spring-biased toward it. The switch 38 has an actuating plunger 42 engaging the lever 37 and continuously internally spring-biased toward it, so that torque is continuously applied to the lever arm 22 of the wire no matter which direction the wire may move.

It will be evident that the wire has suflicient freedom in the tube 23 so that it can turn with respect to the tube but that the wire has a certain amount of frictional engagement with the tube. The wire by virtue of its internal stress which tends to. maintain its curvature, tends to transmit a torque to the lever arm 22 as the loaded portion of the beam of the wire-in-tube is moved linearly transverse to the plane of curvature.

FIGURES 9, 11 and 13 plot torque as ordinate against the deflection of the free end of the cantilever beam as abscissa and FIGURES 10, 12 and 14 plot angular motion of the lever arm of the wire as ordinate against deflection at the free end of the beam.

FIGURES 9 and 10 show the condition for the prior art device where both tube and wire are curved in the same direction in a gradual curvature. FIGURE 9 shows the condition in which the lever is clamped and torque is measured. A very flat curve is obtained. FIGURE 10 shows the condition in which movement of the lever arm occurs and it is seen that a steep curve is obtained. FIG- URES 11 and 12 are similar respectively to FIGURES 9 and 10 except that there is a steep curvature rather than a gradual curvature in the preformed wire and tube. In this case there is a reversal of the relation. The torque curve is very steep and the angular motion curve is very gradual.

FIGURES 13 and 14 show a similar relation for the device of the invention. In this case it will be noted on curve 1 of FIGURE 13 which shows the torque curve with the lever 22 clamped (stationary wire) has a very steep curve and likewise the angular motion curve of FIGURE 14 is very steep and this is a unique combination of properties that were not obtained 'by the prior art device.

FIGURE 13 also plots on curve 2 the flattened torque curve which is obtained when the wire moves. It will be noted that points A, B, C and D there appear and this will be better understood by reference to FIGURES 15 and 16.

FIGURES 16 and 17 show the behavior of a typical displacer 33 which is used to bend the wire and tube assembly. In FIGURE 16 various levels of the fluid on the displacer are shown at A, B, C and D which also represent the levels at which the two switches 35 and 38 operating over the range 35 and 33' respectively could be actuated. FIGURE 15 is related to FIGURE 16 in that the actuating points of the two switches corresponding to the levels on the displacer A, B, C and D are related to the torque and motion output of the wire. It can be seen that as the liquid level falls the torque output of the wire increases and vice versa.

By comparing FIGURES 15 and 16 it will be seen that as the liquid level falls on the displacer 33 the torque increases until the liquid level and torque output reaches point C on the illustration at which point enough torque has been built up to actuate switch 35. A further liquid fall actuates switch 38 at level D. Continued level fall provides an extension of the useful calibration range. In reverse, as the liquid level rises the torque falls off until level B has been reached at which point switch 38 resets, further rise in liquid level resets switch 35 at A. A continued liquid level rise provides an extension of the calibration range at the top of the displacer 33.

It will be evident that there is no particular reference point of the wire with respect to zero in the form of the device in FIGURES 1 to 6, and the motion must therefore be subject to control limit stops in the preferred embodiment. If the wire is actually secured to the tube as by welding or brazing at the outer end or point of application of the load as shown in FIGURE 7 at 27, the wire is confined and the advantages of the device of the invention can be obtained with a reference point which will establish a permanent zero. The angular motion of this form is, however, limited to torsional displacement differential between the wire and the tube which is less pronounced than with the free wire.

In a particular embodiment of the device, which is given merely by way of example, using a stainless steel circular tube and a stainless steel circular wire, the tube had an outside diameter of V inch, and a bore of of an inch and the wire had an outside diameter of of an inch so that the overall clearance between the tube and the wire was of an inch.

In the device of FIGURE 17 the point of loading of the cantilever wire may be moved by sliding the clip 43 from the end to point 43 The tube may be made composite as shown in FIG- URE 8 consisting of one half 44 and another half 45 continuously flanged and welded together at 46. One half may be of one alloy composition and another of another alloy composition. For example, one half of the tube may be of co-nstantan and the other of copper so that there is a difierent-ial expansion effect.

One may be of Invar and one of copper and this differential expansion effect produces a temperature sensing action and also a difference in modulus of elasticity between the two halves of the tube. The wire will be inserted so that the beam plane of curvature will bisect the sandwich or lie in the plane of the weld in the preferred embodiment.

It will be desirable in many cases .as earlier explained to use ditierent metals or other materials for the tube as compared to the wire. The moment of inertia of the tube due to this greater diameter in relation to the diameter of the wire would normally be as great as the wire and generally substantially greater. In many cases the moment of inertia of the tube will be between one and twenty times the moment of inertia of the wire and preferably between four and eight times the moment of inentia of the wire. 7

' While this result can be obtained in many cases of variations in bore and wall thickness of the tube compared to diameter of the wire, in some cases the wire and the tube will be of material having different Youngs modulus, the tube in many cases being of lower modulus material while the wire may be suitably of higher modulus material. Thus in some cases the tube will be of a nonferrous metal as previously described where the wire will be of a 'ferrous metal or even of a higher modulus material such as tungsten. The tube, for example can be of stainless or corrosion resistant steel and the wire can if desired be of higher modulus material such as tungsten. For many applications, however, this is not necessary, and it will be sufiicient to make both the tube and the wire of one of the stainless steel grades.

The operation of the device will be better understood by explaining what happens when the Wire is inserted into a straight tube which forms a beam section. If the curved wire is inserted in the straight tube and the stresses are kept within the elastic limits of the materials involved and both materials have the same Youngs modulus, the combined deflection of the Wire-intube will be determined by the relation deformation radius of each member under load,

where f is the deflection and I is the moment of inertia respectively for the wire and the tube sections.

Thus, if the moment of inertia of the tube is six times the moment of inertia of the wire, it will be evident that the deflection of the wire initially will be six times the deflection of the tube under the same conditions.

The incremental wire curvature will be imparted to the tube along its length in accordance with the relative moments of inertia of the sections. If the initial curvature of the wire is a true arc of a circle, the final curvature of the combination is correspondingly a true arc of a circle of a larger radius.

Under the conditions the wire is stressed in bending with compression on the convex side and tension on the concave side while the tube is stressed in bending with the compression and tension respectively at the opposite sides. a

If now the wire-in-tube combination is subject to defiection within the elastic limit by the load applied at 33 in FIGURE 6 transverse to the plane of curvature. of the wire-in-tube combination, the wire and the tube combination will function similar to a cantilever beam. This will introduce 'a bending moment as Well as a torque moment in the tube and the wire and if the outer end ofthe wire has a transverse lever arm 22 and the lever is restrained as by a spring on the switch with which it is engaged, the lever arm will apply torque proportionally to the deflection of the end of the beam.

Since the wire is free to rotate in the tube, the torque reaction force sustained at the lever arm of the wire outside the tube is limited to the torque forces which can be maintained by the positional relationship of the wire in the tube.

It the reaction should exceed the positioning moment between the wire and the tube, slip will take place until these moments are balanced.

It will be evident that the positioning moment is a function of the prestress loading which in turn is proportional to the free wire deflection. For this reason the developed torque reaction with the tube deflection is proportionately higher as compared to when the prior art wire with conforming curvature of the wire and the tube was used.

It will be evident from FIGURE 15 particularly that it is possible by the present invention to obtain relatively high torque for a given deflection consistent with liberally controlled angular motion as required for actuation of controls and switches. Thus the microswitch 35 in FIG- URE 6 might be adjusted to trip at a torque level C in FIGURE 15 and to reset at torque level A and microswitch 38 might react similarly at torque levels D and B respectively. The desired movement of the wire arm 22 of FIGURE 6 which is associated with the switch requirements continues well beyond the switch actuation points at both ends as shown on FIGURE 15. Progressive movements of the total wire and tube-switch assembly causes flattening of the slope of the torque curve as shown by FIGURE 13, curve 2. The liberal permissible motion in combination with high torque provides wide capability for transmitting either torque of motion selectively than the device of the prior art and is very much simpler to produce and simpler to calibrate.

' Although the lack of orientation of the tube with respect to the wire in the form of FIGURE 6 prevents the use of this device where a zero reference is important, the form of FIGURE 7 will serve amply in this case.

It will be evident that while the invention is preferably applied to a cantilever beam, the beam need not in all cases be a cantilever.

'It will further be evident that the invention will in some cases be applied where the tube is not closed at the free end although in the preferred embodiment the tube will be closed at the free end.

In view of our invention and disclosure, variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of our invention without copying the structure shown, and we therefore claim all such insofar as they fall within the reasonable spirit and scope of our claims.

Having thus described our invention what We claim as new and desire to secure by Letters Patent is:

1. 'In a control torque and motion device operating through a wall, an elastically deflectable tube extending through the wall and having a beam portion beyond the wall which is adapted to deflect elastically, said tube in relaxed position being straight, a wire extending through the interior of the tube and exerting force laterally on the tube along the beam portion, the wire when free from the tube having a curvature along a portion which is to extend inside the tube, the curved portion of the Wire when inside the tube by its residual stress deflecting the tube into a curvature on a radius larger than the radius of curvature of the wire when free from the tube, the wire and the tube both being deflected by each other within the elastic limit of each, lever means on the wire beyond the tube for sensing motion or torque or both of the wire as desired, the wire when in the tube having clearance and being able to apply energy through the lever arm as the tube deflects, means on the beam for applying load to the beam section generally transverse to the plane of curvature of the combination of the wire and the tube when assembled together and free from lateral restraint, and biasing means acting on the lever arm of the wire for biasing the wire under a predetermined load, the biasing means permitting yielding to establish control responsive to the deflection of the beam portion.

2. A device of claim 1, in which the wire and the tube are free to turn with respect to one another throughout the length of the wire.

3. A device of claim 1, in which the wire and tube are secured together near the end of the tube which is remote from the wall.

4. A device of claim 1, in which the moment of inertia of the tube is between one and twenty times the moment of inertia of the wire.

5. A device of claim 1, in which the moment of inertia of the tube is between four and eight times the moment of inertia of the wire.

6. A device of claim 1, in which the wire has a diflerent Youngs modulus from the tube.

7. A device of claim 1, in which the wire has a higher Youngs modulus than the tube.

8. A device of claim 1, in which the tube is a composite of metals of different modulus of elasticity.

9. A device of claim 1, in which the tube is a composite in which different portions of its cross section are of metals of different coefiicients of expansion.

10. A device of claim 1, in which the tube is a composite of two tube halves extending throughout the entire length and joined together by welds, the welds being in the plane of curvature of the combined wire and tube.

11. A device of claim 1, in combination with means on the beam for moving the point of deflecting load application along the beam.

References Cited by the Examiner UNITED STATES PATENTS 2,725,445 11/55 Bosch. 3,067,623 12/62 Kinderman 7417.8

BROUGHTON G. DURHAM, Primary Examiner. 

1. IN A CONTROL TORQUE AND MOTION DEVICE OPERATING THROUGH A WALL, AN ELASTICALLY DEFLECTABLE TUBE EXTENDING THROUGH THE WALL AND HAVING A BEAM PORTION BEYOND THE WALL WHICH IS ADAPTED TO DEFLECT ELASTICALLY, SAID TUBE IN RELAXED POSITION BEING STRAIGHT, A WIRE EXTENDING THROUGH THE INTERIOR OF THE TUBE AND EXERTING FORCE LATERALLY ON THE TUBE ALONG THE BEAM PORTION, THE WIRE WHEN FREE FROM THE TUBE HAVING A CURVATURE ALONG A PORTION WHICH IS TO EXTEND INSIDE THE TUBE, THE CURVED PORTION OF THE WIRE WHEN INSIDE THE TUBE BY ITS RESIDUAL STRESS DEFLECTING THE TUBE INTO A CURVATURE ON A RADIUS LARGER THAN THE RADIUS OF CURVATURE OF THE WIRE WHEN FREE FROM THE TUBE, THE WIRE AND THE BOTH BEING DEFLECTED BY EACH OTHER WITHIN THE ELASTIC LIMIT TO EACH, LEVER MEANS ON THE WIRE BEYOND THE TUBE FOR SENSING MOTION OR TORQUE OR BOTH OF THE WIRE AS DESIRED, THE WIRE WHEN IN THE TUBE HAVING CLEARANCE AND BEING ABLE TO APPLY ENERGY THROUGH THE LEVER ARM AS THE 